Reversible two-stroke internal combustion engine



March 18, 1941.

REVERSIBLE TWO-STROKE INTERNAL COMBUSTION ENGINE Filed July 17, 1959 4 Sheets-Sheet 1 E. o. P. THEGE EIAL 235050 March 18,1941. E. o. P. THEGE ETAL REVERSIBLE TWO-STROKE INTERNAL COMBUSTION ENGINE 4 Sheets- Sheet 2 Filed July 17, 1939 March 1941- E. o. P. THEGE ETAL 5,050

REVERSIBLE TWO-STROKE INTERNAL COMBUSTION ENGINE Filed July 17, 19:59 4 Sheets-Sheet 5 2 w 22 .l/a //b T 9 v 55 March 9- E. o. P. THESE ETAL 5050 REVERSIBLE TWO-STROKE INTERNAL COMBUSTION ENGINE Filed July 17, 1959 4 Sheets-$11661; 4

some Mar. 18, 1941 PATENT OFFICE REVERSIBLE TWO-STROKE INTERNAL COMBUSTION ENGINE Edvin Ossian Parcival'l'hege and Diet Verner Fixn, Stockholm, Sweden, assignors to Aktlcbolaget Atlas-Diesel, Stockholm, Sweden Application July 17, 1939, Serial No. 284,824 In Sweden November 29, 1938 13 Claims.

The present invention relates to reversible two-stroke internal combustion engines having a scavenging pump of the centrifugal compressor tyne driven by the engine.

Since scavenging pumps of the said type must be driven in a certain direction of rotation, it

has hitherto been necessary, when reversing the engine, also to reverse the direction of rotation oi the pump, so that independent of the changed in direction of rotation of the enginethe pump maintams its active direction of movement.

To this end a reversing gear must be included in the transmission gearing between the engine shaft and the pump shaft, which makes it necesllt sary to use a great number of movable parts resulting in a greater risk of running disturbances, and, besides, the length of the engine construction will be rather great. Further, the reversing gear brings about a complication of the no manoeuvring means of the engine, and thus also the risk of incorrectly performed manoeuvring operations will be increased. A still further drawback in using a reversing gear consists in this that it generally brings about a rather an disturbing noise, substantially resulting from the lntermeshing gear wheels.

, The present invention has for its object 'to avoid the said drawbacks and consists substantially in this that the scavenging pump comau prises two centrifugal compressors, one of which is made to be active when running the eng nein the one direction and the second when runnin the engine'in the opposite direction. The two compressors, which for instance may form a wheels active in opposite directions. However, it. is also possible to drive the two compressors in opposite directions, in which case the bucket 4o vanes 01' the two wheels have to be equally directed, so that one pumponly will be active at each direction of rotation of the engine. The two: pumps may preferably, by means of valve devices, be alternately connected to the scaveng- 45 log air rccelver of the engine.

By suchmeans it is obtained that independent of the direction of rotation of the engine one of the centrifugal compressors will be active, whereasthe second compressor idles in the backwward direction. Theme: required-for the idlingotoneottheinthehackward ism null lndtmoumts to the vantilationukonlyotfimvnne-rhedor wheels of the m and k mil; lea than the n loss of My at a reversing gear.

(Cl. 123-4l.)

in such cases, where the engine at the hackward running needs not develop full power, the centrifugal compressor adapted for the said direction oi rotation can he made smaller than that adapted for the forward running, and hit such means the loss of power dueto the corotation of the said compressor at the forward running, the main direction of rotation, will he further decreased.

On the accompanying drawings some emhodilo ments of an arrangement according to the invention are shown diagrammatically. Fig. 1 its. side view of part of the engine, the scavenging pump according to one term of embodiment being shown in axial section. Fig. 2 is a top is view. of the arrangement according to Fig. l and Fig. 3 illustrates diagrammatically part of the pressure conduits of the scavenging air receiver. Figs. 4 to 6 are similar views showing a scavenging pump according to a modified ar-- 2o rangement. Figs. 7 and it are views similar to those of Figs. 4 and 5 and show an emhodiment,

in which the two compressors are driven in opposits directions. Fig. 9 illustrates diagrammatically two separate'valves in the pressure conduits of the compressors. Figs. 1c and 11 show diagrammatically two different emhodiments of means for automatically controlling the. air-flow from the compressors.

In Figs. 1 and 2, l designates part of the combustion engine and 2 the crank shaft thereoi, the free end of said shaft being mounted in a projecting part 3 of the crank casing carrying' the 7 frame 4 of the scavenging pump. The pump twin-pump; may preferably be driven in the same direction and provided with bucket vane consists of two separate housings 5 and 6, re- 35 spectively, having associated helices I and 8, respectively, and bucket vane wheels 9 and l0, respectively, which are secured to a common shaft H mounted in the pump frame I. The air intake of the pump 5, I, 9 is denoted by I! and 40 that of the pump 6, 8, Ill by H. Thepressure conduit connected to the helix '1 of the former pump is denoted by. H and the pressure conduit connected to the helix 8 of the second pump by Ii. The said two pressure conduits-ll and I5 are in communication with a common pressure conduit Ii communicating with the scavenging air receiver ll of the engine. As apparent from Fig. 3, a flap valve II is mounted in the common pressure conduit Ii at the connecting place of the pressureconduits II and Item! by means of thesoidvalvetheoneortheotheroftheconduits ll and I5 can be shut oi! from the conduit Ii. Thetwopumpsaredrivenfmmtheenglue shaft {hymeons o! a toothed wheel gearing [9, ll

20, 2|, 22 located between the pumps, the shafts of the intermediate wheels 20, 2| being mounted in the pump frame 4. I

The pump 5, I, 9 is assumed to be adapted for forward running and the pump 6, 8, ID for backward running. Thus, in the former case the pump 5, 1, 9 is active and forces the air through the conduit I4, whereby the flap valve I8 shall take up the position shown by full lines in Fig. 3, so that the air enters the receiver I! through the conduits I4 and I 6, the conduit I5 being shut off. In this case the pump 6, 9, I0, the bucket vanes of which are turned in a direc tion opposite to that of the vanes of the pump 5, I, 9, is inactive.

When reversing the direction of rotation of the engine I from forward to backward running also the direction of rotation'of the pumps is reversed, and the pump 6, 8, III will be active, whereas the pump 5, I, 9 will be inactive. In this case the flap valve I8 shall be moved to the position shown by dotted lines in Fig. 3, so that a free communication is obtained between-the conduits I5 and I B and simultaneously the pipe I4 is shut off.

The embodiment shown in Figs. 4 to 6 difiers from that one above described in this respect only that here the two pumps 5 I, 9 and 6, 8, I9 are provided with a common air intake 23 located between the pumps and that the toothed gearing I9 to 22 is located at the inside of the pump unit between said unit and the engine. The action of this arrangement is the same as that of the embodiment according to Figs. 1 to 3.

The embodiment shown in Figs. '7 and 8 differs from that one according to Figs. 4 and 5' in this respect that the two bucket vane wheels 9 and I9, the vanes of which are to be equally directed, are placed on separate shafts Na and IIb, respectively, mounted in the frame 4 and driven from the engine shaft -2 through separate gearings 24, 25, 26 and I9 to 22, respectively. As visible from Fig. 7 the gearing driving the vane wheel 9 contains three gear wheels 24, 25 and 26, whereas the gearing driving the vane wheel I I] contains four gear wheels I9, 20, 2I and 22. As a consequence, the shaft I Ia and the vane wheel 9 will obtain the same direction of rotation as that of the engine shaft 2, whereas the shaft I II) and the vane wheel I will be caused to rotate in the opposite direction. Thus, since the vanes of the two wheels 9 and I 0 are equally directed, the two compressors will be alternately active, the one at the running of the engine in the one direction and the other at the opposite direction of running. 1 a If desired, separate flap valves may obviously be placed in each one of the pressure conduits I4 and I as shown at I8a and I8b in Fig. 9, the valve bodies being pivotally connected by a rod 2! so that when closing the one valve the other will be opened and vice versa, and the valves need obviously not have the shape of flap valves, but may be of any desired construction.

If desired, the adjustment of the valves may be performed automatically at the reversing of the engine through the air pressure from the temporarily active-compressor or also by the aid of mechanical, pneumatical or hydraulical means of any suitable construction.

Fig. 10 shows an embodiment, in which a single flap valve I80 is pivotally connected at 23 at the place of connection of the pipes I4, I5 and I6, similar to the embodiment shown in Fig. 3. The weight of the valve body I8c is balanced by a counter-weight 29 securedto the valve by means of a lever arm 30. If the compressor communicating with the pipe I5 be active, the air forced through said pipe will turn the valve to the position shown by full lines, whereas, if the other compressor forcing air through the pipe I4 be active, the valve will obtain the position shown by dotted lines, the'pipe communicating with the temporarily idling compressor being shut off.

Fig. 11 illustrates diagrammatically fluid-operated (pressure-oil or pressure-air) means for adjusting the valve I8d. The said valve is pivotally connected at 3| at the place of intersection of the pipes I4, I5 and I6 and has a lever arm 32 connected to it, which by means of a rod 33 is operatively connected to a piston 34 capable of reciprocating in a cylinder 35 having inlet pipes 36 and 31, respectively, for a pressure fluid opening at both ends of the cylinder. The said pipes also open into a cylindrical valve housing 38 at both ends of the same, a valve body 39 being capable of reciprocating in said housing and being connected to a. manoeuvring lever 40 by means of a rod 4|. A pressure fluid from any suitable source of pressure is supplied to the valve housing 38 through a pipe 52.

In the valve position shown, the pressure fluid enters into the cylinder 35 through the pipe 36 at the righthand end causing the piston 34 to move to the left-hand end as shown, thereby causing the valve I8d to take up the position shown by full lines closing the .pipe I4 and opening the pipe I 5. If the valve 38 be moved towards the right by operating the lever 40, the pressure fiuid will enter at the left-hand end of the cylinder 35 through communication between the pipes I4 and I6 in-.

stead of between the pipes I5 and I6 as in the former-position. Obviously, the piston valve 38 may be in connection with the reversing means of the engine, so that'the flap valve I8d will be operated automatically when reversing the engine,

On the annexed drawings the centrifugal compressors have been shown as one-wheeled, onestage compressors, which, however, is not necessary, since the same may be made with a plurality of wheels as multi-stage compressors without departing from the scope of the invention. Besides, the compressors may be placed at other places with respect to the engine, such as for instance at the one side of the engine, without the manner of driving the compressors being thereby altered.

Whatwe claim is:

1. A reversible two-stroke internal combustion engine and a scavenging pump of the centrifugal compressor type driven by said engine, said pump comprising two centrifugal compressors, the one being arranged to-be active in the one direction of running of the engine and the second in the opposite direction of running.

2. A reversible two-stroke internal combustion engine and a scavenging pump of the centrifugal compressor type driven by said engine, said pump comprising two centrifugal compressors, the one being arranged to be active in the one direction of running of the engine and the second in the 0pposite direction of running, said compressors be- 1 compressor type driven by said engine, said pump '75 comprising two centrifugal compressors, the one being arranged to be active in the one direction of running of the engine and the second in the opposite direction of running, said compressors being rotated in opposite directions and provided with bucket vane wheels having equally directed vanes.

it. A reversible two-stroke internal combustion engine, a scavenging pump of the centrifugal compressor type driven by said engine, said pump comprising two centrifugal compressors. made as a twin-pump, and a shaft common to both compressors, one of which is arranged to be active in the one direction of running of the engineand the second in the opposite direction of running,

5. A reversible two-stroke internal combustion engine, an air receiver on said engine, a scaveng ing pump of the centrifugal compressor type driven by said engine, said pump comprising two centrifugal compressors, and valve means for alternately bringing said compressors in communication with said air receiver, one of said compressors being arranged to be active in the one direction of running of the engine and the second in-the opposite direction of running.

6. A reversible two-stroke internal combustion engine, an air receiver on said engine, a scavenging pump of the centrifugal compressor type driven by said engine, said pump comprising two centrifugal compressors, and automatic valve means for alternately bringing said compressors in communication with said air receiver, one of .said compressors being arranged to be active in the one direction of running of the engine and the second in the opposite direction of running.

7. A reversible two-stroke internal combustion engine and a scavenging pump'of the centrifugal compressor type driven by said engine, said pump comprising two centrifugal compressors, the one being arranged to be active in the one direction of running of the engine and the second in the opposite direction of running, said compressors having separate air intakes.

8. A reversible two-stroke internal combustion engine and a scavenging pump of the centrifugal compressor type driven by said engine, said pump comprising two centrifugal compressors, the one being arranged to be active in the one direction of running of the engine and the second in the opposite direction of running, said compressors having a. common airintake.

9. A reversible two-stroke internal combustion engine, a shaft driven by said engine, a scavenging pump of the centrifugal compressor type comprising two centrifugal compressors, and a common transmission gearing between said shaft and said compressors, one of which is arranged to be active in the one direction of running of the engine and the second in the opposite direction of running.

10. A reversible two-stroke internal combustion engine, a shaft driven by said engine, a scavenging pump of the centrifugal compressor type comprising two centrifugal compressors, and a common transmission gearing between said shaft and said compressors, one of which is arranged to be active in the one direction of running of the engine and the second in the opposite direction of running, said transmission gearing being located between the said two compressors.

11. A reversible two-stroke internal combustion engine, a shaft driven by said engine, a scavenge ing pump of the centrifugal compressor type comprising two centrifugal compressors, and a common transmission gearing between said shaft and said compressor, one of which is arranged to be active in the one direction of running of the engine and the second in the opposite direction of running, said transmission gearing being cated between the engine and the pump.

'12, A reversible two-stroke internal combustion engine, a shaft driven by said engine, a scavenging pump of the centrifugal compressor type comprising two centrifugal compressors and sepbeing arranged to be active in the one direction of running of the engine and the second in the opposite direction of running, the compressors adapted for the forward running of the engine being made larger than that one adapted for the backward running. I

- EDVIN OSSIAN PARCIVAL 'I'HEGE, OLOF VERNER FrxnN. 

